Mozilla Firefox 21 web browser for desktop and mobile were released a few days ago, the Desktop and Mobile releases are packed with some new features, several enhancements and security fixes. Check How to install/update Mozilla Firefox 21 for many Linux distribution such as “Fedora, CentOS, RHEL, Ubuntu, Linux Mint, …” and the release notes down below.

Ubuntu repository will be updated soon with the latest stable release of Mozilla Firefox version 21 so, no need to add additional repository simply run the update manager and it will be installed along with your system updates. If you would like to install update Mozilla Firefox only you can use these commands.